Destruct system improvement

ABSTRACT

A pyrotechnic cord assembly is provided with voids for safety in handling and storage. The voids are filled with bridging pyrotechnic material at the time of final assembly.

Uite States Patent 1 6,2 7

Willard et al. 1 Dec. 19,1972

[5 DESTRUCT SYSTEM IMPROVEMENT FOREIGN PATENTS OR APPLICATIONS [72] Inventors: Robert C. Willard; Jimme M. Craig; Lloyd J. Jackson, all of China Lake,

Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy [22] Filed: Oct. 28, 1970 211 ApplfNoJ: 84,680

[52] US. Cl. ..102/27 R, 102/70 R [51] Int. Cl ..F42b 19/08 [58] Field of Search ..l02/27 R [56] References Cited UNITED STATES PATENTS 3,238,876 3/1966 Allen ..l02/27 R 3,260,202 7/1966 Bryla ..lO2/27 R 3,91l I882 Great Britain .vl02/27 F 9,003 1889 Great Britain ..l02/27 F 25,403 9/1936 Australia ..l02/27 F Primary ExaminerVerlin R. Pendegrass Attorney-R. S. Sciascia, Roy Miller and Gerald F. Baker [57] ABSTRACT A pyrotechnic cord assembly is provided with voids for safety in handling and storage. The voids are filled with bridging pyrotechnic material at the time of final assembly.

2 Claims, 6 Drawing Figures PATENTEnnzc 19 I972 3. 706. 277' FIG. IA. 1;;

I PRIOR ART) FIG. 2A.

(PRIOR ART INVENTORS. ROBERT C. WILLARD JIMMIE M. CRAIG LLOYD J. JACKSON BY ROY MILLER ATTORNEY.

GERALD F. BAKER I AGENT.

DESTRUCT SYSTEM IMPROVEMENT CROSS REFERENCE TO RELATED APPLICATIONS sembly when a cut is made along dotted line 15. In the final assembly the loop of safety wire 14 is also attached to a lanyard or other pull cable 18. When safety wire 14 is pulled out, the spring 20 reacts against hous- The disclosed method and article of manufacture Ing 19 to force firing P 16 Into the Primer of ignition pertains to an improvement in the pyrotechnic train more fully disclosed in U. S. application Ser. No. 884,084 filed Dec. 11, 1969 and the flare system in which the pyrotechnic trains are presently utilized is more fully disclosed in U. S. application Ser. No. 683,095 filed Nov. 8, 1967 and now U. S. Pat. No. 3,478,687 issued Nov. 18, 1969. The subject matter of the patent is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION In an effort to prolong the useful life of serial flares, a hot air balloon device has been substituted for the usual parachute. As the hot air balloon suspended flare burns, the ratio of flare weight to balloon lift decreases to a point where the system begins to rise. Since illumination varies inversely as the square of the distance, any appreciable rise of the system is undesirable. Also, after theflare has completely burned out, it is desirable to remove the balloon from the air for aircraft safety.

The venting and destruct system described in the above referenced application was designed to cut a vent in the balloon at a predetermined time after deployment to check the ascent of the system and thereafter to completely destroy the remaining lift of the system at a time closely coinciding with flare burnout.

In the manufacture of the pyrotechnic trains and the subsequent attachment of the pyrotechnic trains to the balloon it was soon learned that the pyrotechnic train as constituted was hazardous to handle and store.

The present invention involves a method ofmanufacture which results in a product which is much less hazardous in the assembly and storage thereof and in the final placement in the assembly in which it is to be used. This is accomplished by providing in each pyrotechnic cord connection a space between cord ends and access means in each connector so that the space may be filled with bridging pyrotechnic material in final assembly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. I is a plan view partly in section of the initiating end of a pyrotechnic cord according to the invention illustrating changes over the prior art as shown in a similar view in FIG. IA;

FIG. 2 is a plan view partly in cross section of a portion of the pyrotechnic train corresponding to the prior portion shown in FIG. 2A; and

FIG. 3 is a plan view of a fitting in a portion of the train which corresponds to the prior section shown in FIG. 3A.

DETAILED DESCRIPTION OF THE INVENTION In the prior art device shown in FIG. 1A, as well as in the instant invention, a length of safety fuze 24 is ignited by an initiator 22 when struck by a firing pin 16. Firing pin 16 is normally held against action of a spring when safety wire 14 is in place. Safety wire 14 comprises a complete loop and remains intact until final asdevice 22. In the prior device as shown in FIG. 1A, the safety fuze 24 was not shielded. In FIG. 1, a Faraday shielding 21 is shown covering the safety fuze 24 and the shielding is held in place on the housing 19 by a resilient sleeve 23.

Safety fuze 24 is designed to ignite a second length of safety fuze 34 as well as a measured length of propellant cord 28 after a predetermined time. For this purpose, in the prior art, a T fitting 30 (FIG. 2A) was provided which was crimped onto the length of safety fuze with the length of pyrotechnic cord 28 intimately connected within the T. According to the present invention this T fitting is replaced with a cross fitting 31 (FIG. 2) which is crimped to the cord 24 and cord 34 as well as the propellant cord 28. The pyrotechnic cords, however, do not touch within the fitting but are so arranged that a void is left which will later receive a sized plug of pyrotechnic material. In the prior assembly, cord 34 was connected to a final length of propellant strand 48 by a simple straight connector FIG. 3A). FIG. 3 illustrates how a T fitting replaces the straight fitting as shown in FIG. 3A to provide another void between safety fuze 34 and a final length of propellant cord 48.

At final assembly, plugs 32 are removed and replaced with similar plugs having pellets of pyrotechnic material fastened on the inner ends thereof. The material used in the connecting pellets is selected for low sensitivity to electrostatic charge, impact, and friction and the entire system is physically grounded during assembly handling and installation operations.

By this invention, therefore, a destruct assembly comprising pyrotechnic cords has been devised which is much less hazardous to manufacture and install than the prior devices without any sacrifice of efficiency.

What is claimed is:

1. In a pyrotechnic transfer train assembly, including a plurality of measured lengths of safety fuse, a plurality of lengths of propellant strand and connecting means between measured lengths of safety fuse and propellant strand, the improvement comprising:

said connecting means comprising a plurality of tubular fittings receiving and securing the ends of at least one of said lengths of fuse and at least one of said lengths of strand and providing one additional tubular passageway;

each said length of fuse and strand being secured in said fitting with the said ends in spaced relation in line with each other and said one additional tubular passageway whereby a space void of explosive material exists between said ends and whereby said space may be filled with explosive material through said additional passageway.

2. The transfer train of claim 1 including a first tubular fitting having four tubular openings and connecting a first and a second length of safety fuse as well as a length of propellant strand; and

a second tubular fitting connecting said second length of safety fuse with a second length of propellant strand.

l i 1 i 

1. In a pyrotechnic transfer train assembly, including a plurality of measured lengths of safety fuse, a plurality of lengths of propellant strand and connecting means between measured lengths of safety fuse and propellant strand, the improvement comprising: said connecting means comprising a plurality of tubular fittings receiving and securing the ends of at least one of said lengths of fuse and at least one of said lengths of strand and providing one additional tubular passageway; each said length of fuse and strand being secured in said fitting with the said ends in spaced relation in line with each other and said one additional tubular passageway whereby a space void of explosive material exists between said ends and whereby said space may be filled with explosive material through said additional passageway.
 2. The transfer train of claim 1 including a first tubular fitting having four tubular openings and connecting a first and a second length of safety fuse as well as a length of propellant strand; and a second tubular fitting connecting said second length of safety fuse with a second length of propellant strand. 